Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Porous semiconductors are promising material in comparison to bulk materials as they offer high surface to volume ratio. It enhances their optoelectronic properties, as well as lattice mismatch, and can be handled by controlling their porosity that significantly alters the band gap present in them. Among them, Group III nitrides exhibit high saturation voltage, high thermal stability and wide band gaps ranging from 3.4 eV for GaN up to 6.2 eV for AIN in the case of wurtzite crystal structure.
Recently, GaN micro- and nanostructures, such as porous layers and nanowire arrays, have attracted great researchers because of their distinct properties such as enhanced luminescence, high sensitivity and selectivity in chemical sensing, low dislocation density, relaxing lattice and thermal mismatch-induced strain and suppressing quantum confined stark effect in lnGaN/GaN quantum wells, from a bulk or an epitaxial thin film.
Over the last decade, huge research is being done on gas sensing semiconductors materials such as ZnO and SnO2. Among these gas sensor materials, Group III-nitride is of great importance as they can work in severe climatic conditions such as high/low temperature, high humidity etc. Group III-nitride such as GaN with different morphologies such as porous structures, nanowires, and nanotubes etc. has been synthesized, and are investigated for gas sensing properties. Colloidal graphite grown on GaN substrate has been used as H2 gas sensor, and it demonstrated a limit response to exposure of 100 ppm H2/N2. Pd/AIGaN/GaN field effect transistor (FET) hetero-structure was used as an H2 gas detector and showed lower limit less than 1 ppm. A sensitivity of 4% is measured from metal composite nanoclusters on GaN nanowires when exposed to 1 ppm H2/N2 at room temperature.
In last few years, passivation of GaN has been thoroughly explored to handle the issues such as current leakage, carriers trapping in light emitting devices and enhancing the conduction mechanism in high electron mobility transistors. Sulfur-based compounds such as sodium sulfide and ammonium sulfide are mainly used due to their strong bonding with III-V semiconductor; in particular, octadecylthiol (ODT) and thioacetamide (TAM) have been employed to treat GaP, GaN, and GaAs. Nanostructures of GaN, as well as its epitaxial layers, have been passivated with inorganic sulfides to explore the effect of passivation on the gas sensor. However, to the best of knowledge of inventors of the present application, the conventional sensors and methods of detecting gas(es) suffers from a disadvantage that they could not achieve the desired performance characteristics.
There is therefore a need in the art of a gas sensor that can overcome the limitations associated with conventional sensors while exhibiting high sensitivity of gas detection under different temperate conditions. The present invention satisfies the existing needs, inter alia, others and provides H2 gas sensor that is highly sensitive at room temperature.